PEWAUKEE -- Firefighters on Tuesday morning, July 31 responded to the scene of a two-alarm fire at NCL Graphic Specialties in Pewaukee. The call came in around 12:30 a.m.

Division Chief Frank Dekan

When crews arrived on scene heavy fire was coming from the roof of structure. Officials say 20 employees were inside the facility when the fire broke out. Everyone made it out safely.

"They all went to a rally point when they got out, right behind us, and did an accountability," said Division Chief Frank Dekan.

Division Chief Frank Dekan says that quick thinking allowed firefighters to stay out of the building -- and stay safe.

"It’s full of paper. What NCL does is stock rolls of paper and cardboard. So where the fire was, was all rolled paper and cardboard," said Dekan.

Shortly after crews began to attack the fire from the air part of the roof collapsed -- and chemicals stored inside exploded.

"There were some stored chemicals on-site because of their operations -- mainly in 55 gallon drums and there were explosions. One of them was a larger explosion," said Dekan.

The fire was so intense, the closest hydrants couldn't keep up with the demand.

"We had to set up a tinder operation on Redford Blvd. to truck water in, in addition to using the city's water system," said Dekan.

Authorities say due to the product stored in the building, the seat of the fire was difficult to access. Additionally, a portion of the roof collapsed onto the source of the fire. As a result, firefighters had to wait for a demolition crew to arrive and remove the roof -- before they could get to the fire.

"When the roof collapsed, it protected the paper and we could not get the water on the paper rolls -- which just caused a headache for all of our crews and that's why it is taking so long because we just have to wait to pull it all apart," said Dekan.

An employee watching nearby told FOX6 News she doesn't know when she will return to work, but she's grateful her co-workers and part of the plant are still standing.

"The best thing is everybody got out safely," said employee.

At one point, roughly 100 firefighters from Pewaukee and surrounding departments were on the scene. Additionally, Waukesha County hazmat crews are also on scene, monitoring air and run off from the building. There are no environmental concerns.